Wind turbines as a source of electrical power are rapidly gaining importance worldwide. The blades (airfoils) are one of the more costly and technically demanding subcomponents of a wind turbine. For best aerodynamic performance, wind turbine blades require a complex shape incorporating continuously variable twist and taper from the central hub to the outer tip. The high power output of megawatt-class utility scale wind turbines justifies production of complex glass fiber composite blades requiring a significant amount of skilled manual labor.
However, this labor-intensive blade manufacturing approach is ill-suited to mass-producing economic blades for small home-scale wind turbines. One prior art approach is to manufacture constant-section blades by pultrusion of glass-reinforced thermoset polymer, but this approach cannot deliver the optimum tapered, twisted blade shape. Small blades 1 meter or less in length may be readily and efficiently produced by automated injection molding as a single solid part, but this process is ill-suited to longer blades, since injection molding does not work well with thick cross sections that occur in root (inboard) regions. Somewhat longer blades may be produced by injection or compression molding of two separate blade halves corresponding to low and high pressure surfaces of the blade, which are subsequently bonded together with adhesive to form a single hollow blade. However, this approach requires purchase of two full-sized molds instead of one, skilled labor is required to assemble the two halves correctly, and the requirement of adhesive compatibility limits the choice of resins that may be used.